Recently, various types of digital contents have been produced and distributed exponentially with the advancement of web and Internet techniques. Such a change in the environment is creating a huge demand for web searching, and the rapid growth of a global search company such as Google for example is considered to result from properly satisfying search demand for users' web contents in line with the changed environment.
As-well known in the art, a question and answer technique for web searching is a technique in which when a user inputs required information in form of a question in a natural language, a system searches for an answer to the user's question from a document and presents it. This question and answer technique is an application technique that comprehensively employs a natural language processing technique, an information extraction technique, and the like, and it is studied for limited domains and documents due to its level of difficulty. Namely, the conventional method uses a scheme of processing a question for a limited domain with a limited answer type and extracting an answer thereto.
In this regard, various technical developments related to such question and answer were made as text retrieval conference (TREC) established in 1992 created a question and answer track in the late 1990s, but it was mostly limited to Factoid questions and some descriptive questions for limited domains due to a technical limitation. And, in the late 2000s, a technical advancement has been achieved to process even a comprehensive question and answer type for an open domain in the question and answer technique in line with the development of a language processing technique, an information extraction technique, a meaning analysis technique, and the like.
As described above, over the flood of web contents and information growing in arithmetical procession, the existing information searching has a limitation in satisfying users' demands for information, and in order to overcome this, various discussions and techniques for a web environment such as a web 2.0, a semantic web, and the like, are mentioned. However, the eventual purpose of such discussions is how to precisely discover information suitable for the users' demand and favorably present it. As a result, the eventual purpose of the web technique will be a question and answer technique.
Namely, because the conventional method simply processes a question for domains limited to limited answer types and extracts an answer thereto, there is a limitation in satisfying users' demands (e.g., the efficiency of document searching, accuracy of extraction of an answer, etc.) for information searching.